Once upon a time, in the good old days, Americans celebrated Christmas in their public schools. They sang hymns, hung stockings, and decorated trees. And nobody complained.

There's just one problem with this bleak winter's tale: It's not true. Despite what you might hear about our contemporary "War on Christmas," holiday celebrations have sparked dissent in American public schools for more than a century. By pretending otherwise, we miss an opportunity to teach our children something important about America.

Ground zero for this year's controversy is Waterbury, Conn., where one principal barred Christmas symbols - including depictions of Santa Claus - from his elementary school. The story made it all the way to a television spot on Fox News' Fox and Friends, where an angry local school board member joined the Rev. Rick Warren in condemning the decision.

Meanwhile, the blogosphere lit up with righteous holiday indignation. "To all you liberal, p.c. global-warming nut jobs, you disgust me!" one post blared. "This nation was founded on Christian values - it's sad we have moved away from those values." Another post added that, back in the day, "no one protest[ed] against these holidays as they do now."

So let's go back to 1906, more than a decade before the ACLU was founded, when Jewish families in New York City staged a one-day boycott of public schools. The reason? School Christmas celebrations.

A committee of Jewish leaders told the board of education that it particularly objected to "the singing of denominational hymns" and "the use of the Christmas tree." Such rituals were "inflicting repugnant religious convictions on the schoolchildren," they argued.

One Yiddish newspaper said school Christmas programs were "shmad shtik" - that is, an effort to convert Jews. Another paper argued that the Christmas celebrations violated the state constitution's separation of church and state.

When the school board turned a deaf ear, Jews turned on their heels. On Christmas Eve that year, New York Jews declared a one-day school strike. On Manhattan's Lower East Side, an estimated 25,000 children stayed home. "Empty Schools: Tens of Thousands of Jewish Children Shun the Christmas Tree," a Yiddish paper exulted. "Hurrah for the Jewish Children!"

But thousands of other Jews shunned the strike, reflecting a stark division in the community. One Jewish school official urged Jews to ignore "agitators" and listen to "the more intelligent Jews of this city," who regarded Christmas rituals as harmless. "I have no objection to Christmas trees, holly, mistletoe, and similar decorations," he added.

The following year, New York barred hymns and other "religious content" from holiday celebrations in the schools. But it continued to allow Christmas symbols, as the New York Times happily reported on Dec. 25, 1907. "Santa Claus and Christmas trees were very much in evidence everywhere," the Times declared. "Representatives of the Board of Education, of the Christian ministers, and of the Hebrews admitted that they had no ground for complaint."

But controversy would continue to hound Christmas in the schools. In the late 1940s, Jewish complaints about Christmas rituals in a suburban Boston school prompted threats of a new boycott - against Jewish-owned stores. "If you Jews don't stop interfering with the Christian Gentile and mind your own business, word will be sent out by 'United Gentiles' to withhold all trade from the Jews," one newspaper warned.

When the Supreme Court barred school prayer in the '60s, some districts actually increased the religious content of their Christmas celebrations to compensate for the banned prayers. Across the country, Jews faced the same dilemma as always: whether to object, and to whom, and by how much.

Jews haven't been the only dissenters. Take the current dispute in Waterbury, where Jehovah's Witnesses have objected to holiday decorations. So have members of the city's Pentecostal community, who view popular icons like Santa Claus as slights to the true meaning and sanctity of Christmas.

"It's ridiculous," said one Pentecostal parent, who has pulled her children out of school during holiday celebrations. "There is a separation of church and state, and this is a public school."

But Americans disagree about that separation, and they always have. That's why the "War on Christmas" is an educational opportunity, if we have the guts and imagination to seize it. Whether they celebrate the holidays or not, let's hope our schools devote a few minutes to teaching kids about the history of this dispute. They'll learn a lot about America, no matter what they think of Santa Claus.

Jonathan Zimmerman teaches history at New York University, lives in Narberth, and is the author of "Whose America? Culture Wars in the Public Schools" (Harvard University Press). He can be reached at jlzimm@aol.com.